Ultralong room-temperature phosphorescence materials based on sodium carboxymethyl cellulose: Enhanced phosphorescence performance via third-component regulation and large-area flexible fabrication

Polymer-based room-temperature phosphorescence (RTP) materials hold great promise for a wide range of applications. However, the development of ultralong natural polymer-based RTP materials, especially those with flexibility, still remains a formidable challenge. In this work, a series of sodium carboxymethyl cellulose (CMC-Na)-based RTP materials are facilely constructed by doping different amounts of 4-carboxyphenylboronic acid (CPBA) into CMC-Na matrices. Interestingly, adding boric acid (BA) as a third-component to the CMC-Na/CPBA system leads to the formation of a tighter intermolecular hydrogen bonding network, significantly enhancing their RTP performance. The longest phosphorescence lifetime of CMC-Na/CPBA/BA increases from 528 ms to 1154 ms, accompanied by a bright blue afterglow extending from 5 s to 10 s. Both CMC-Na/CPBA and CMC-Na/CPBA/BA exhibit RTP emission switching reversibility under alternating treatments of water vapor fumigation and heating. More importantly, transparent and flexible RTP films are prepared by incorporating a small amount of polyethylene glycol (PEG) as a regulator into CMC-Na/CPBA/BA, and can be easily fabricated over large areas using a simple coating-drying method. Furthermore, the prepared CMC-Na-based RTP materials demonstrate potential for applications in information encryption. This study provides an effective strategy for enhancing RTP performance and enabling large-area preparation of flexible natural polymer-based RTP films.